Process for treating hydrocarbon containing organically combined fluorine



Patented Dec. 18, 1945 CONTAINING OBGANICALLY FLUOBINE Frederick a.Frey, Bartlesvliie, om, assignmto Phillips Petroleum Company, acorporation of Delaware No Drawing. Original application August 80,

1943, Serial No. 500.553. Divided and this applloa tion February 2,1945, Serial No. 575,928

8 Claims.

The present invention relates to a method of removing organic fluorinefrom hydrocarbon mai, terials and more particularly from hydrocarbonmaterials which contain organic fluorine a a reby processes in whichfluorinemontainingcatalysts are used. Another obieotis to providesmethod for the liberation of hydrogen fluoride from hydrocarbonmaterials containing organic suit of having been prepared by processesinvolvfiuorlneand fixation of hydrogen fluoride so libin: use offluorine-containing catalysts, such as 'er'ated.' Numerous other objectswill hereinafter boron trifiuoride but more especially hydrogen appear.fluoride. In accordance with the present invention, the This applicationis a division of my copending removal of organic fluorine fromhydrocarbon application Ser. No; 500,553, filed August 30, 1943, lomaterials containing the same is accomplished by which has-issued asPatent No. 2,377,546, June 5. tr ins the hydr r n mat ri l wi h l mi1945, and which is a continuation-in-part of my impregnated with analkali metal compound ca- Drior application Ser. No. 398,361, flied June16, pable of combining with hydrogen fluoride. ef- 1941, now Patent No.2,347,945, issued May 2, 1944. fecting decomposition-of the organicfluorine oomydrosen fluoride is finding use to an increas- 16 p u dspresent in the hydrocarbon withfconsein: extent as a catalyst inhydrocarbon converque t l er ti n f h o o d and sions, especiallyalkylation of ar-amp with l bination' of the hydrogen fluoride soliberated with fins to make motor and aviation fuel components th lkalit l pound carri d y e a111- 01 high anti-knock rating. It is also beingused mine. The decomposition of the organic fluorine 38 8 a in ndrefining agent for motor and compounds isefi'ected by the employment ofeleaviation fuels and lubricating'oil. The crude hy- 'vated temperaturesin the treatment. other condrocarbon products obtained by such processesditions being such as to favor this decomposition contain substantialamounts or organically comand combination of the hydrogen fluoride setfree,

v'bined fluorine which must be removed i ord r with the alkali metalcompound. Preferably the tomeet specifications. Products made with'otheras temperature lies between 150 and 550 F.. fluorine-containingcatalysts, hief among which The alumina may be in any form which issufis boron trifiuoride, likewise contain combined ficiently adsorbentto allow impregnation with mnic fluorine. e the alkali metal compound.Usually andprefydrocarbon materials that have been prepared erably thealumina is in the form of either bauxite by processes of the foregoingtype in which fluoor activated alumina. This alumina isimpregrine-containing catalysts are used contain small noted with fromapproximately '2 to approxi- Droportlons of organic fluorine in the formr mately 10% by weight of'the alkali metal comorsanic compounds whichare believed to be prepound, and any moisture is removed, whereupondominantly alkyl and/o aryl fluorides, H tothe resulting material isthen ready for use in fore this organic fluorine has been removed by ca011N118 inventionpflsing the hydrocarbon material through a solid Asthealkali metal compound I may employ porous contact material of the typeof activated any alkali metal compound which is .capable of alumina orbauxite. Unfortunately, however, concomblning with hydrogen fluoride.The preferred t materialscf this ype may contain up .to so alkali metalcompound is the alkali hydroxide. much as 20 per cent by weight ofsilica, wh 40 Instead of the hydroxide Imay employ any alkali app re lreacts .wlth'hydrofiuoric acid formed met l salt or compound which iscapable of by decomposition of the organic fluorine comblnina with hydron fiuol'ide- It is preferred to P unds to form silicon tetrafluoride.This silicon use an alkali metal compound which combines tetrafiuorideis highly objectionable because conwith the hydro fluoride give thealkali i tact of it with moisture liberates hydrofluoric acid fluoride.For example, one moi of the alkali which is c di ly corrosive. and atthe same metal hydroxide reacts with two mols of HF to time 599081195elatinous" silicic acid which acgive the alkali metal acid fluoride andone mol 0? cumulates until the equipment is plugged. Morewater. One molof alkali metal fluoride react 1. over the resultant loss of fluorine inthe form of with one moi of HF to give the alkali acid fluosillcontetrafiuoride is economically undesirable. ride directly. Accordingly,the alkali metal com- The p in ipal object of the present inventionpound whichis preferably and almost invariably s o Provide for theremoval of organic fluorine employed will beeither the alkali metalhydroxide from hydrocarbon materials containing th same, or the alkalimetal; fluoride. In some circum- Another object is to remove organicfluorine from stances it may be found possible or desirable tohydrocarbon materials that have been prepared use the alkali metaloxide. Use of alkali metalv with 6% by weight of potassium hydroxide.

carbonate or bicarbonate is ordinarily not desirable because of theliberation of C: which contaminates the hydrocarbon stream. As thealkali metal I prefer to employ the more common sodium andpotassium'although the use of lithium is not precluded. Potassium ispreferred. The other alkali metals, cesium and rubidium, al-

though operative, are prohibitively expensive and are not used. The termalkali metal" as used herein, therefore, comprehends the true alkalimetals found in group I of the periodic system, and does not includeammonium.

By the treatment of the present invention, the organic fluoridescontained in the hydrocarbon are decomposed, forming in parthydrofluoric acid which reacts with the alkali metal hydroxide orfluoride, preferably potassium hydroxide or fluoride, to form the alkalimetal acid fluoride, preferably potassium acid fluoride, before itreacts with the silica in the alumina. When the alu- -minaimpregnatedwith the alkali metal compreferably carried out in a streamor current of an inert carrier gas which serves to carry off thehydrogen fluoide as liberated, the resulting mixture of carrier gas andhydrogen fluoride being conveyed away to a suitable recovery point wherethe hydrogen fluoride is recovered by cooling and condensation, thecarrier gas being non-condensible.

' For use in accordance with the present invention, the alumina in theform of either bauxite or j activated alumina may be impregnated with anaqueous solution of the alkali hydroxide or fluoride, dried, and placedin a closed treating cham her. The hydrocarbon material is then passedinl either the liquid or the vapor phase, Preferably the former, throughthe contact mass at a space velocity of l to 10 volumes of liquid pervolume of contact mass per hour. The temperature maintained at thecontact chamber is preferably betact' mass which comprises bauxite andpotassium fluoride is then reused for removing additional organicfluorine.

While speciflc details'of the preferred modeof operation have been givenin the foregoing for purposes of illustration, it is to be understoodthat the invention is not limited thereby, but is to be taken as limitedsolely by the langauge of the appended claims.

I claim:

l. A process for treating hydrocarbon containing organically combinedfluorine to remove said fluorine therefrom which comprises subjectingsaid hydrocarbon containing a minor quantity of organically combinedfluorine to the action of dehydrated adsorbent silica-containing aluminaimpregnated with an alkali metal hydroxide at a reaction temperature offrom 150 to 550 F. and for a period of time such that said aluminacatalyzes decomposition of the organic fluorine compounds presentin thehydrocarbon with consequent liberation of the fluorine as hydrogenfluoride and combination of hydrogen fluoride so liberated with saidalkali metal hydroxide to give the corresponding alkali metal acidfluoride, said period of time being such that the hydrocarbon eiiluentfrom said treatment is substantially free of organically combinedfluorine.

2. A process for treating'hydrocarbon containing organically combinedfluorine to remove said fluorine therefrom which comprises subjectingsaid hydrocarbon containing a minor quantity of organically combinedfluorine to the action of dehydrated silica-containing bauxiteimpregnated' with an alkali metal hydroxide at a reaction temperature offrom 150 to 550 F. and for a period of time such that said bauxitecatalyzes decomposition of the organic fluorine compounds present in thehydrocarbon svith consequent liberation of the fluorine as hydrogenfluoride and combination of hydrogen fluoride so liberated with saidalkali metal hydroxide to give the corretween about 150 and 550 F., andthe pressure,

although not critical, is preferably between 15 and 500 p. s. i.

Following is a speciflc example of the practice of the presentinvention:

' Example A debutanizer overhead effluent from the alkylation of a C4hydrocarbon fraction with an olefln in the presence of HF as a catalystis passed through a bed of calcined bauxite impregnated The rate of flowof the hydrocarbon is 5 liquid volumes of hydrocarbon per volume ofcatalyst per volume of contact mass per hour. The temperature ismaintained at about 180 F. The pressure is sufficient to maintain thehydrocarbon in the liquid phase. Substantially complete removal of theorganic fluorine takes place, and the eiiluent hydrocarbon material isfree from silicon tetrafluoride. When spent, the contact mass is heatedin a stream of a butane at approximately 700 to 800' l". to drive 01! HFwhich is recovered by cooling and condensation and returned to thealkylation step. The resulting regenerated consponding alkali metal acidfluoride, said period of time being such that the hydrocarbon emuentfrom said treatment is substantially free of organ ically combinedfluorine. I

3. A process for treating hydrocarbon containing organicallyv combinedfluorine to remove said fluorine therefrom which comprises subjectingsaid hydrocarbon containinga minor quantity of organically combinedfluorine to the action of dehydrated silica-containing adsorbent aluminaimpregnated with from 2 to 10 per cent by weight of alkali metalhydroxide at'a reaction temperature of from 150 to 550 F. and for aperiod of time such that said alumina catalyzes decomposition of theorganic fluorine compounds present in the hydrocarbon with consequentliberation of the fluorine as hydrogen fluoride and combination ofhydrogen fluoride so liberated with said alkali metal hydroxide to givethe corresponding alkali metal acid fluoride, said period of time beingsuch that the hydrocarbon effluent from said treatment is substantiallyfree of organically combined fluorine.

4. A process for treating hydrocarbon containing organically combinedfluorine to remove said fluorine therefrom which comprises subjectingsaid hydrocarbon containing a minor quantity of organically combinedfluorine -to the action of dehydrated silica-containing adsorbentalumina impregnated with potassium hydroxide at a reaction temperatureof from to550 F. and for a period of time such that said=aluminacatalyses decomposition of the organic fluorine compounds present in thehydrocarboniwithconsequent liberation o! the fluorine as hydrogenfluoride and combination of hydrogen fluoride so liberatedperiodoftimcbein: suchtbatthe hydrocarbon with said potassium hydroxideto give potassium acid fluoride, said period of time being such that thehydrocarbon emuent from said treatment is substantially free 01organically combined fluorine. I

5. A process for treating hydrocarbon containing organically combinedfluorine to remove said fluorine therefrom which comprises subjectingsaid hydrocarbon containing a minor quantity of organically combinedfluorine to the action of the organic fluorine compounds present in thehydrocarbon with consequent liberation of the fluorine as hydrogenfluoride and combination of hydrogen fluoride so liberated with saidpotassium hydromde to give potassium acid fluoride, said eiiiuent fromsaid treatment is substantially free of organically combined fluorine. v

. 6. A process for treating hydrocarbon containing organically combinedfluorine to remove said fluorine therefrom which comprises subjectingsaid hydrocarbon containing a minor quantity of organically combinedfluorine to the action or dehydrated silica-containing bauxiteimpregnoted with 6 per-cent by weight of potassium hydroxide at areaction tem'perature or from 1st to 550 F. and for a period oi timesuch that said bauxite catalyzes decomposition of the organic fluorinecompounds present in the hydrocarbon with consequent liberation of thefluorine as hydrogen fluoride and combination of hydrogen fluoride soliberated with said potassium hydroxide to give potassium acid fluoride,said period of time being such that the hydrocarbon emuent from saidtreatment is substantially free of organ-

